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SSP 321 The Golf 2004 Running Gear .pdf



Nom original: SSP 321 The Golf 2004 Running Gear.pdf
Titre: SSP321 The Golf 2004 Running gear
Auteur: VK-21

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Service Training

Self-study programme 321

The Golf 2004
Running gear
Design and function

With the refined safety running gear of the Golf,
which is configured for both sporty and
comfortable driving, VW has set a further
standard in the development of running gear
technology. With the aim of developing the best
underpinnings in its class, a dynamic running
gear system was created that keeps the driver
away from unpleasant surprises in any situation.

The running gear of the Golf features an
optimised suspension strut axle, multi-link rear
axle, completely new electronic power steering
and the newest generation of ESP and brake
assist system to offer a unique synthesis of
best-in-class driving comfort and, at the same
time, best steering and driving response.

S321_179

NEW

This self-study programme shows the design and
function of new developments!
The contents will not be updated.

2

For current inspection, adjustment and repair
instructions, please refer to the relevant
service literature.

Important
Note

Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Front axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Rear axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Steering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Brake system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Wheels and tyres. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

Foot pedal cluster . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Test yourself . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

3

Introduction
The running gear
Once again, the running gear of the Golf sets a standard in its class. To achieve this a suspension strut
axle, perfectly optimised in many ways, has been installed. With regards to driving dynamics and driving
comfort, the new four link rear axle is also ground-breaking.
The electromechanical power steering of the Golf supports the vehicle's driving characteristics
in a remarkable way. To do this, it transmits a precise steering feeling and adapts the steering forces
harmoniously as speed increases.
In addition to the Golf, the Touran and Audi A3 also currently use this running gear platform.









Optimised suspension strut axle based
on the McPherson principle

Direct anti-roll bar connection with
ratio of 1:1

Electromechanical power
steering



Brake servo with dual
rate map characteristic



4

Floor mounted accelerator pedal with non-contact
accelerator pedal position senders

Electronic stabilisation program
based on MK 60 system from
Continental Teves

The Golf can be equipped with standard, sports or heavy duty running gear. The various running gear
systems differ in the spring, damper, anti-roll bar equipment and the mounting elements.
The sports running gear is lowered by 15 mm compared with the agile and comfort-orientated standard
running gear. The body height of the vehicle with heavy duty running gear is 20 mm higher than on the
standard running gear version.



Four link rear axle



4motion drive, optional



Tyre monitoring system,
optional





Brake assist system

Track and camber on rear
axle can be adjusted separately

S321_135



Wheel designs in
15", 16" or 17" versions

5

Front axle
The front axle
The Golf has a McPherson front axle with bottom wishbones and wheel locating suspension struts.
The front axle offers optimal comfort at a high level of stability.

Anti-roll bar

Subframe

Suspension
strut

Wheel bearing
Wishbone suspension

housing
Console

Coupling rod

S321_007

Wheel bearing

6

Subframe

The subframe comprises of three parts and is
made of aluminium. It is joined to the body at six
points. With this type of connection, the body is
stiffened in the front area. The optimal layout of
the bonded rubber bushes in the wishbones and
suspension strut mountings has a positive
influence on the driving dynamics and body
acoustics.

Console
Subframe
Console

S321_022

Key:
= Bonding point to body

Wheel bearing

The wheel bearings are of the 3rd generation.
This type of component is a compact wheel
bearing unit comprised of wheel hub and wheel
bearing, which is bolted from the interior to the
swivel mounting by four bolts.
The advantage of this wheel bearing is that the
bearing play no longer has to be adjusted.

S321_020

7

Front axle
Suspension strut
The spring used is a combination of cylindrical
coil spring and polyurethane auxiliary damper.
The coil spring is made from high tensile steel
and is drawn in at the ends. The damping
characteristic of the coil springs is linear.
The polyurethane auxiliary spring has a
progressive damping characteristic.

Auxiliary damper

Coil spring

S321_039

Suspension strut mounting
The suspension strut mounting is a bonded
rubber bush. By decoupling the spring and shock
absorber connection to the body, the damping
force is absorbed separately by the body. In this
way, pretension in the damper mounting is
prevented. This positively influences rolling
comfort and reduces the transfer of noise from
the road surface to the body.
The mounting features a soft damping
characteristic in the direction of normal travel. In
this way, an improvement is achieved in driving
comfort and acoustics.
In the lateral direction, the mounting is designed
to be stiffer. This measure positively influences
the driving dynamics and the steering response.

8

S321_041

Swivel mounting
The swivel mounting is joined to the suspension
strut by a clamp-type connection.
At the lower level it is attached to the wishbone
via a guide joint.

The wheel bearing unit is bolted to the swivel
mounting. Depending on the version, either a
bolted or integrated swivel mounting is installed.

Integrated swivel mounting

Bolted swivel mounting

Clamp-type
connection

Suspension strut Swivel mounting

Suspension
strut

Swivel mounting

Clamp-type
connection

Brake carrier

Brake caliper

S321_043

S321_019

Wheel bearing
unit

Guide joint

Wheel bearing
unit

Wishbone suspension

Bolted connection

Subframe

The wishbones form the lower connection
between the body and swivel mounting.
Depending on the engine, they are made from
cast iron or sheet metal and are joined via
bonded rubber bushes to the consoles of the
subframe.

Wishbone suspension
S321_021

9

Front axle
Anti-roll bar
The tubular anti-roll bar is joined directly to the
suspension strut via a coupling rod in a ratio
of 1:1.
The advantage compared to the Golf’98 is that a
higher degree of anti-roll stabilisation is
achieved with the same tube diameter.
Suspension strut

Bushes

Coupling rod
Anti-roll bar

Subframe
S321_045

The anti-roll bar is mounted on the subframe by
means of two bushes. The positive connection
of the bonded rubber bushes prevents relative
movements between anti-roll bar and bonded
rubber bush.
Instead of turning in the rubber bush, the
rotational movements of the anti-roll bar are
absorbed in the mounting. In this way, a high
degree of efficiency is achieved.

Anti-roll bar

Bonded rubber
bush
S321_134

Absorbed
relative movement

10

Bearing

The drive shafts

Left-hand
drive shaft

Right-hand drive
shaft

Installed in the Golf is the track proven drive
shaft concept with short and long drive shafts.
The shorter shaft on the left-hand side is solid.
The longer shaft on the right, however, is a
hollow tubular construction.

Intermediate
shaft

S321_046

Intermediate
shaft

S321_048

On higher powered engines, the drive shafts are
of the same length. This is made possible by an
intermediate shaft, which is mounted additionally
on the crankcase. This drive shaft concept is
advantageous in that, even during full
acceleration, there are no repercussions on the
steering and straight running of the vehicle from
driving forces. Furthermore, pulling to one side is
also avoided.

S321_049

11

Rear axle
The front wheel drive rear axle
The rear axle of the Golf is of the compact four
link design. On each side it has three suspension
links (lower link, track rod and upper link) and a
trailing arm.

With a predetermined alteration in the wheel
position during cornering, a light understeer is
achieved due to the natural opposing steering
force of the outer wheel (self steering response
or toe-in steering).

This layout means that longitudinal and lateral
forces are almost completely separated from
each other. In this way, a very high level of
driving stability and comfort are achieved.

Steel spring
Anti-roll bar
Damper
Upper link

Subframe
Bearing bracket

Track rod

Lower link
Trailing arm
S321_171

12

Subframe
The subframe is a welded construction made
from steel. It is bolted directly to the body. The
body mounting points on front wheel drive and
4motion drive systems are identical.

S321_027

Wheel carrier

Wheel bearing

The wheel carrier is a forged metal construction
made from steel with a moulded stub axle to
mount the wheel bearing.

The wheel hub and wheel bearing form one
component. The wheel bearing is bolted to the
stub axle of the wheel carrier by means of a
stretch bolt. In this way, the necessary bearing
preload is achieved (2nd generation wheel
bearing).

Stub axle

Wheel bearing

Wheel carrier

Stretch bolt

S321_029

13

Rear axle
Four link principle
On the four link axle of the Golf 2004,
longitudinal and lateral connections are
separate. The advantage is that no compromise
had to made between comfort and driving
dynamics.

The front mounting (trailing arm) is not subjected
to lateral forces and has therefore been made
very soft. Cracks and grooves running across the
road surface are absorbed easily.

Longitudilal

Trailing arm

Track rod

Lateral force

Top link

Bottom link

S321_018

As a comparison, the following illustration shows the force distribution on the double wishbone
suspension of the Golf’ 98.
Longitudinal force

Trailing arm

Upper wishbone
Lateral force

Lower wishbone

S321_190

14

The 4motion rear axle
The driven rear axle has been modified on the
subframe, anti-roll bar, wheel carrier and wheel
bearings.

The advantage of this axle design is that the floor
assembly on vehicles with front wheel and
4motion drive systems is the same with regards to
the body mounting points.

Subframe
Wheel bearing

Anti-roll bar

S321_031

Wheel carrier

15

Rear axle
Subframe
The subframe is a welded construction made
from aluminium. It also supports the rear
differential. It is bolted to the body by means of
oversized bonded rubber bushes. In this way,
noise reduction is promoted thanks to isolation of
the body.
An additional aluminium cross member, bolted
in position, serves as a means of increasing
rigidity in the lower area by complementing the
subframe. The use of aluminium means that a
weight saving of approx. 7 kg has been
achieved.

Subframe

Cross member
S321_033

Bonded rubber bush

Wheel carrier

Wheel bearing

The wheel carrier was modified geometrically to
accommodate the drive from the rear axle
(introduction of modified wheel bearing and
drive shaft).

The wheel bearing installed here is of the 3rd
generation (as installed in the front axle).

Wheel carrier

Wheel bearing

S321_035

16

Steering
The steering
The electromechanical power steering supports the driving response of the Golf. To do this, it conveys a
precise feel for the vehicle and the road. As speed increases, the steering forces are adapted
harmoniously. Disrupting factors from bumps in the road surface are filtered out as far as possible.

Overview

Steering column

Steering wheel

S321_053

Universal joint shaft

Electromechanical power
steering

17

Steering
The steering wheels
Installed as standard is a 4-spoke PU steering
wheel. PU (polyurethane) is a very strong
synthetic material, which is good to work with
and can be recycled. As an alternative, a
steering wheel with soft leather covering and
one-piece cast magnesium frame is available.
During assembly, the airbag module is installed
in the steering wheel mechanically and can only
be removed if the steering column is disengaged.
This is an effective anti-theft measure to prevent
unauthorised removal of the driver airbag.

S321_124

The steering wheel features a weight-optimised framework cast from magnesium.
The design can be seen in the cross sectional diagram of the multi-function steering wheel.

Cross-section based on wooden steering wheel

Leather covering of

Mounting for left multi-

Mounting for right

function switch

multi-function switch

right spoke trim

left spoke trim

Wood veneer shell

Leather covering

PU foam covering

Magnesium frame
S321_196

18

Leather covering of

Sheet metal plate

Various designs of 3-spoke steering wheel will be available as an option.

Design 1:
The steering wheel is of the 3-spoke design,
finished in either leather or a combination of
leather and aluminium.

S321_012

Design 2:
The steering wheel is of the 3-spoke design,
finished in wood and leather. The multi-function
steering wheel features an audio and telephone
function.

S321_014

Design 3:
The steering wheel is of the 3-spoke design,
finished in leather. The multi-function steering
wheel features an audio and telephone function
and also Tiptronic.

S321_010

19

Steering
The steering column
The reach and rake adjustment of the steering
column is mechanical. For optimal adaptation to
the driver's requirements, it can be adjusted up
and down by 50 mm and back and forth by
60 mm.

Fixing of the steering wheel in position is by
means of a multi-plate bundle with ten steel
plates.
Five plates in the horizontal plane make reach
adjustment possible.
The other five plates are installed in the vertical
plane and make rake adjustment possible.

Multi-plate bundle for
reach adjustment

Multi-plate bundle for
rake adjustment
S321_084

Connection of the steering column to the dash module carrier is by means of an assembly bracket
pressure cast from aluminium.

20

Principle of the clamping function
The clamping function is provided by two rollers
that are pushed up a ramp to fix the steering
wheel in position. In this way, the multi-plate
bundle is pressed together via a thrust piece.



Due to the fact that no gear teeth are used in the
clamping mechanism, adjustment is infinitely
variable.

Multi-clamp bundle released

Thrust piece
Plates for rake
adjustment
Roller

Ramp
Plates for reach
adjustment
S321_128


Multi-clamp bundle clamped

Thrust piece
Plates for rake
adjustment
Roller

Ramp
Plates for reach
adjustment
S321_126

21

Steering
Crash concept
As part of occupant safety, the steering column
and the universal joint shaft are designed to slide
into each other. In this way, the steering column
and the steering wheel will not be pushed
towards the driver if the front end of the vehicle
deforms.

The steering column tube and universal joint
shaft are designed so that the steering column is
decoupled from the steering gear in the event of
the steering gear being forced inwards in a
crash. This prevents the steering wheel from
jutting against the driver as a result of further
deformation of the front end.

S321_130

The cradle and console are joined together by
means of a shear plate. In the event of a crash, a
defined force is placed against the shear plate
by the movement caused from the impact of the
driver against the cradle.

The geometrical design of the shear
plate means that a progressive force/travel
characteristic is achieved.

Cradle

Shear plate

S321_173
Console

22

The electromechanical power steering

S321_137

The electro-mechanical power steering is an
active steering system, which is directly
dependent on road speed, the steering force and
the steering angle.

The Golf is fitted as standard with an electromechanical power steering system.
This steering system consists of steering box and
an electric motor with control unit.
The system is installed on the subframe.
The steering assistance from the electric motor,
which is flanged in parallel to the toothed rack, is
transmitted via a second pinion (drive pinion) to
the toothed rack.

Data is transferred via the drive train CAN data
bus. The control unit is flanged to the electric
motor.

Control unit
Steering force

Electric motor

sender

S321_057

Steering pinion
Toothed rack

Drive pinion

Steering column

Steering angle
sender

Further information can be found in SSP 317 "The dual pinion electromechanical power
steering".

23

Brake system
The brake system
The basis for good braking properties is provided by a newly designed brake system. The Golf is fitted as
standard with the newest generation of ESP and brake assist system.

Overview

Brake servo

ESP unit

S321_155
Rear wheel brake

Brake cable
Handbrake

Front wheel brake

24

Brake lines

The brake equipment
Engine

Front brakes (single piston
floating caliper brake)

55 kW85 kW

Ø280x22

Rear brakes

Ø255x10

Ø260x12

S321_156

Integrated swivel mounting
100 kW110 kW
and
77 kW TDI
with
DSG 02E

Ø288x25
S321_164

S321_166

S321_158

bolted swivel mounting
147 kW
and
118 kW
TDI

Ø286x12 / Ø286x12

Ø312x25

S321_168
S321_160

bolted swivel mounting
177 kW

Ø345x30

Ø310x22

S321_170
S321_162

bolted swivel mounting

25

Brake system
The dual rate booster brake servo
In all left-hand drive vehicles, a 10" brake servo
is installed.
Right-hand drive vehicles are equipped with a
tandem brake servo of 7/8" in dimension.
A main new feature is the introduction of the
"dual rate characteristic".
The inside of the brake servo is modified, which
results in a progressive characteristic. In this way,
higher brake pressures are available than on
conventional brake servos, even at low pedal
forces. Braking forces are still imparted softly
during normal operation however.

S321_078

Brake pressure

Standard characteristic
Dual rate characteristic

Pedal force

26

S321_037

The anti-lock braking system ABS/ESP
Continental/Teves MK 60
A new ESP unit of the product family MK 60 is installed. The main new features are:


Active wheel speed sender without forwards and reverse travel recognition.



Combined yaw rate/lateral acceleration sensor. This sensor is compatible with the CAN system.



Installed in the ESP unit is the brake pressure sender. The brake pressure sender was installed
until now on the tandem brake master cylinder.



New ESP warning lamp.

S321_192

Hydraulic unit with brake pressure sender (G201)

S321_060

Sender spring contacts

Brake pressure sender

Installed as an exclusive ABS system is the MK 70. As this component only features the ABS
function (4 inlet and 4 outlet valves), it is smaller and lighter than the MK 60 system.

27

Brake system
The brake pressure sender (G201)
It measures the pressure applied at the brake
pedal by the driver. To ensure a higher level of
safety, the sensor supplies two pressure signals
independently of each other.

These are sent at the same time as two opposing
voltages. The control unit constantly compares
these with each other.

S321_176

S321_175
1.

Measuring chamber

2. Piezo resistive thick film sensor element

6. Flexible thick film membrane

3. Sensor electronics and signal amplifier

7. Piezo bridge elements within measuring bridge

4. Contact springs to control unit J104

Electric switching
The sensor is joined via 4 contact springs to
control unit J104 (4). Two contacts serve as a
means of supplying power, the other two provide
two independent pressure signals.

28

5. Piezo resistive measuring bridge

S321_178

Construction
The sensor works on the principle of piezo
resistance. To do this, use is made of the change
in conductivity of the materials from structural
deformation. Four piezo resistive measuring
elements, which are switched together to form a
bridge (5), are installed on a membrane (6).

Piezo resistive measuring elements are resistors
made from semi-conductor material. The function
is similar to that of bi-metallic strips.

Function
As pressure increases, the length of the
membrane (6) changes and also the piezo
resistive measuring bridge (5) connected to it.
This change in length imparts force on the piezo
bridge elements in the measuring bridge (7),
which alters the charge distribution within the
piezo elements.

With a change in the charge distribution, the
electrical properties of the piezo bridge elements
also change. These are proportional to the
pressure and are transmitted as an amplified
sensor signal to control unit J104.

Self-diagnosis

Effects of failure

The pressure sensor is monitored by the
electronic control unit via both output signals.
If both signals deviate from each other within the
tolerance level, a fault is diagnosed by the
control unit.

In the event of pressure sensor failure, the ESP
function is reduced to ABS and EBD (electronic
brake pressure distribution).

29

Brake system
The optimised hydraulic brake servo (OHBS)
The most effective way to supply vacuum
pressure to the brake servo is to utilise the
vacuum from the intake manifold on the engine.
On petrol engines with automatic gearboxes, the
vacuum pressure available at the intake
manifold can drop significantly in certain
operating conditions (cold start phase). This can
have a negative impact on the comfort of brake
actuation.

The cause of this is the opening of the throttle
valve under load, which drastically reduces the
vacuum in the intake manifold. Until now, the
necessary vacuum for such situations was
provided by an auxiliary unit (e.g. electric
vacuum pump).
In the Golf 2004, a new path has been found.

Map characteristic at
Point of brake servo

800 mbar vacuum

Brake pressure

actuation

Lower vacuum level (e.g. cold start)

Braking assistance by means of OHBS function
Foot pressure

30

S321_062

Function
The loss of braking assistance, as a result of
insufficient vacuum pressure, is balanced out
with an active and controlled build-up of brake
pressure from the ESP hydraulics. To enable this
control, measurement of the pneumatic forces in
both chambers of the brake servo (BS) is
necessary. The pressure difference is a direct
benchmark for the maximum amount of braking
assistance available. If the pressure in both
chambers is equaI, the point of brake servo
actuation is reached. Thereafter, a further
increase in braking force is only possible, without
additional braking assistance, by an increase in
foot pressure on the brake pedal.

If this is the case, a controlled build-up of brake
pressure is initiated by the ESP hydraulics.
Compared to conventional braking assistance,
the driver will notice no difference here with
regards to the force required at the brake pedal
and braking comfort.
To enable the controlled build-up of brake
pressure, the use of new solenoid valves is made
to switch to ESP regulated mode.
The degree to which these valves is opened can
be controlled on a time basis. In this way, the
pressure patterns can be adapted to each
situation.

Stored in the ESP control unit J104 is the specified
map characteristic for the build-up of brake
pressure, depending on the pressure difference
in both servo chambers. If the intake manifold
vacuum is insufficient, the point of actuation is
reached even at brake pressure levels below the
specified amount.

31

Brake system
Differential pressure sensor
The sensor measures the pneumatic pressures in
both chambers of the brake servo.

S321_064

Installation position of differential pressure sensor shown as cross-sectional diagram

Vacuum
pressure
Differential

chamber

pressure sensor

Working pressure
chamber

Brake servo

S321_066

32

Signal application

Effects of failure

The differential pressure sensor calculates the
difference in brake servo pressure conditions to
atmospheric pressure. For OHBS regulation,
however, only the pressure in the vacuum
pressure chamber is used.

If the signal from the working pressure chamber
should fail, an entry is made in the fault memory.
The OHBS function remains intact.
In the event of signal failure in the vacuum
pressure chamber, an entry is made in the fault
memory and the brake system warning lamp
K118 will light up.

The exchange of ESP and CAN data
The ESP control unit exchanges data with other control units of the onboard electrical system.

J220
Motronic control
unit
J104
ESP control unit
J217
Automatic gearbox
control unit

J533
Data bus diagnostic
interface

J492
Four-wheel drive
control unit

J527
Steering column
electronics control unit
G85
Steering angle sender

Diagnosis connection

J500
Electromechanical
power steering
control unit

J285
Control unit with display in dash
panel insert

S321_180

Drivetrain CAN data bus

Dash panel CAN data bus

Diagnostic CAN data bus

Data bus wiring

33

Brake system
The handbrake
The new design means that the amount of space required in the centre console has been minimised. In
this way, additional stowage facilities have been created behind the handle. The lever is pressure cast
from magnesium. This resulted in a weight saving of more than half that of the steel version.

S321_073

The toothed segment is joined positively to the
bearing bracket. In the neutral position, the pawl
is engaged with the toothed segment and the
brake lever is locked.

S321_201

34

When the release button is pressed, the pawl is
pulled away from the toothed segment and the
brake lever is free to move.

S321_203

Wheels and tyres
The wheels and tyres
Equipment overview

Tyre size

Profile

Rim size

Rim type

195/65/ R 15 91 T

Summer

6 J x 15 offset 47

Steel

195/65/ R 15 91 T/H

Summer

6.5 J x 15 offset 50

Alloy

195/65/ R 15 91 T/H

Winter

6 J x 15 offset 47

Steel

205/60/ R 15 91 H

Summer

6 J x 15 offset 47

Alloy

205/55/ R 16 91 H/V/W

Summer

6.5 J x 16 offset 50

Alloy

205/55/ R 16 91 Q

Winter

6 J x 16 offset 50

Alloy

205/45/ R 17 91 H/V

Summer

7 J x 17 offset 54

Alloy

Spare wheel of emergency
type
T125/70/ R 18
Spare wheel of conventional
type
or Tirefit

-

3.5 J x 18

-

Tyre monitoring system
The tyre monitoring system is a software module in the ABS control unit. It detects slow punctures and
gradual tyre pressure loss at the wheel.

More detailed information can be found in self-study programme SSP 319 "The Golf 2004
Electrical system".

35

Pedal cluster
The pedal cluster
The foot pedal cluster was adapted to the Golf.
Accelerator pedal, clutch and brake actuation
are of a modular design.

To remove the accelerator pedal
module, please use special tool T10238
or T10240.

S321_087

The clutch position sender G476
Fitting location
The clutch position sender is clipped onto the
master cylinder. This sender detects when the
clutch pedal is actuated.

Signal application
With the clutch pedal actuated,


the cruise control system is switched off and



the amount of fuel injected is reduced briefly
to prevent gear change jolts.

Clutch pedal with clutch
position sender

36

S321_195

How it works
Bearing bracket

The master cylinder is attached to the bearing
bracket via a bayonet connection.
When the clutch pedal is actuated, the plunger
moves the piston in the master cylinder.

Plunger

Clutch master
cylinder

Clutch position
sender
Piston with
permanent magnet

S321_204
Pedal travel

Clutch pedal not pressed

Piston with
Plunger

permanent magnet

When the clutch pedal is not pressed, the
plunger and piston are in the rest position.
The electronic evaluation feature of the clutch
position sender sends a voltage signal to the
engine control unit, which is 2 volts under the
supply voltage (battery voltage).
The engine control unit thereby detects that the
clutch pedal is not pressed.

Clutch pedal pressed

S321_224
Switch point
(Hall sender)
Clutch position

Voltage signal to engine

sender

control unit

Piston with

Plunger

permanent magnet

When the clutch pedal is pressed, the plunger is
pushed together with the piston in the direction
of the clutch position sender. At the front end of
the piston is a permanent magnet.
As soon as the permanent magnet passes over
the switch point of the Hall sender, the electronic
evaluation feature now only sends a voltage
signal of 0 to 2 volts to the engine control unit. In
this way, it detects that the clutch pedal is
pressed.

S321_226

Switch point
(Hall sender)
Clutch position

Voltage signal to engine

sender

control unit

37

Pedal cluster
The accelerator pedal position senders G79 and G185
Both accelerator pedal position senders are part of the accelerator pedal module and operate without
contact as inductive senders.
Advantages
- No wear as senders operate without contact
- No basic setting for kick-down necessary as
sender is part of accelerator pedal module,
which therefore does not result in tolerances
between accelerator pedal and vehicle body

Signal application
The engine control unit uses the accelerator
pedal position sender signals to calculate the
amount injected.
S321_217

Accelerator pedal with accelerator
pedal position senders

Effects of signal failure
In the event of failure in one or both senders, an entry is made in the fault memory and the electronic
power control (EPC) warning lamp will be activated.
The convenience features, such as cruise control or engine braking control will be deactivated.

If one sender fails

If both senders fail

the system will adopt the idle position. If the
second sender is detected at idle within a
defined test period, normal driving mode will be
authorised again.

the engine will only run at increased idling speed
(max. 1500 rpm) and will no longer respond to
input from the accelerator pedal.

If a full throttle input is made, speed will increase
only slowly.

38

Construction
The accelerator pedal module comprises of an
accelerator pedal, the pedal end stop, the
mechanical components to convert rotational
motion and both accelerator pedal position
senders G79 and G185.

Accelerator pedal

Small metal plate

The senders are joined to a circuit board and
each consist of an exciter coil, three receiver coils
and electronics for control and evaluation. For
reasons of safety, both senders operate
independently of each other.
Mechanical
components
S321_219

Cover
Circuit board

The mechanical components of the accelerator
pedal module convert leverage movement of the
accelerator pedal into straight line motion.

A small metal plate is attached so that when the
accelerator pedal is actuated, it is brought in line
just short of the circuit board.

Accelerator pedal not pressed

Accelerator pedal pressed

Mechanical
Mechanical

components
Exciter coils

components

Small metal plate
Small metal plate
S321_220
S321_222

Circuit board

Area of

Circuit board

receiver coils

39

Pedal cluster
How it works

J248

Diesel direct injection
system control unit

Supplied with 5V of power, the pedal electronics
generate a high frequency alternating voltage,
which results in the build-up of an electromagnetic alternating field. This electro-magnetic
alternating field affects one moving small metal
plate. As this happens, a further electromagnetic alternating field is generated around
the small metal plate.

Electronics for
Exciter coils

evaluation

Small metal plate
S321_228

Receiver coils

This location-dependent alternating field
influences the receiver coils, inducing a relevant
alternating signal there.

Electro-magnetic alternating

Electro-magnetic

field of small metal plate

alternating field of
exciter coil

The strength of the induced alternating voltage
depends largely on the position of the small
metal plate. Each position results in a different
coverage of the small metal plate to the receiver
coils.
In the idle position, the coverage is at its lowest
and, therefore, so is the induced alternating
voltage.

S321_230

In the full throttle, i.e. kick-down position on
automatic gearboxes, coverage is at its greatest
and, therefore, so is the alternating voltage.

Small metal plate in

Small metal plate in

idle position

full throttle position
Kickdown area

Evaluation
The electronics for evaluation set the alternating
voltages of the three receiver coils at a common
value, they amplify them and bring the output
voltages of the three receiver coils together into
the equation. Following voltage evaluation, the
result is converted into a linear voltage signal
and sent on to the engine control unit.

Signal voltage in volts

Accelerator pedal position travel

Driver input percentage
S321_232

Full throttle stop
Accelerator
pedal end stop

40

Service
The axle geometry
Installed in the Golf is an adjustable rear axle, e.g. track and camber can be changed independently of
each other.

The track is adjusted via an eccentric bolt
between lower link and subframe.

S321_116

S321_120

The camber is adjusted via an eccentric bolt. This
eccentric bolt joins the link to the subframe.

To adjust the camber, special tools

S321_118




shock absorber set T10001 and
ring spanner T10179 are required.

41

Service
Special tools

Designation

Tool

Application

T10179
Ring spanner

For adjusting camber on rear axle
in conjunction with shock absorber set T10001

S321_114

T10219 (1)
Sleeve

(1)

For renewing bonded rubber bush on wishbone of
front axle
(2)

T10219 (2)
Drift

S321_112

T10149
Support

For adjusting unladen weight position of bonded
rubber bushes on front and rear axle

S321_194

T10238 (1)
T10240 (2)

(1)

Release tool for accelerator pedal module,
LHD (1) and
RHD (2)

(2)

S321_200

42

Test yourself
1.

What is so special about the four link rear axle?
a) Oversteer is achieved by means of a predefined change in the wheel position during cornering.
b) Separation of longitudinal and lateral connection.
c) Cracks and grooves running across the road surface are absorbed easily.

2.

Of which components is the electro-mechanical power steering comprised?
a) Steering column, mechanical steering gear and hydraulic pump.
b) Steering angle sender, steering column, steering force sender, control unit, electric motor and steering gear.
c) Steering angle sender, steering column, steering force sender, yaw rate sender and swivel mounting.

What is the role of OHB-V?
a) OHB-V measures the brake pressure applied by the driver via the brake pedal.
b) The loss of braking assistance, as a result of insufficient vacuum pressure, is balanced out with an active
and controlled build-up of brake pressure from the ESP hydraulics.
c) Due to modifications to the interior of the brake servo, it makes high braking pressures available even at
low pedal forces.

1.) b, c; 2.) b; 3.) b
Answers

3.

43

321

© VOLKSWAGEN AG, Wolfsburg, VK-36 Service Training
All rights and the right to make technical alterations reserved
000.2811.42.20 Technical status 09/03

❀ This paper was manufactured from pulp that
was bleached without the use of chlorine.


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